Interface engineered self-induced and cascading nanozyme for colorimetric and photothermal dual-mode pesticide sensing

Nanozymes have witnessed significant advancements in bio/chemical sensing, however, single signal response and the need for additional hydrogen peroxide (H2O2) still have posed challenges to their analytical practicability. Herein, this work exemplified the structure-activity relationship of a self-supplying H2O2 and cascading peroxidase nanozyme (ZrFc@CPN) based on a hierarchical ferrocene metal-organic framework (ZrFc-MOF) nanoflower loaded with copper peroxide nanodots (CPNs). Thereinto, CPN can release H2O2 and Cu2+ under an acidic ambient to initiate a Fenton-like catalysis, simultaneously, the released H2O2 can also be utilized by ZrFcMOF moiety with peroxidase-like activity to function as a cascading nanozyme. These integrated features of ZrFc@CPN enabled oxidizing 3,3 ',5,5 '-tetramethylbenzidine (TMB) into oxidized TMB (oxTMB) without additional H2O2, generating colorimetric and photothermal temperature signals. Alluringly, the conceptually designed ZrFc@CPN nanozyme was applied to quantify glyphosate (GLP) herbicide that can significantly inhibit mimic activity, thereby blocking the oxidation of TMB into oxTMB and causing a subsequent decrease of both colorimetric and photothermal dual-mode signals. Notably, ZrFc@CPN exhibited wider response ranges compared with pristine ZrFc-MOF because GLP can inhibit the catalytic performance of CPN in addition to inhibiting the ZrFc-MOF peroxidase mimicking activity. Comprehensively, exceptional catalytic and sensing performance as well as its ease of manufacture enabled the hierarchical flower-like ZrFc@CPN nanozyme promising for sensitive GLP detection, furnishing a novel tactic to construct a versatile and feasible nanozyme sensing platform.